A Philippine nurse held by Islamic State (IS) group in the Libyan city of Sirte said on Monday that she and her colleagues had been forced to treat militants and give them medical training.

The nurse is from a group of seven women, one man and a 10-month-old child who are being repatriated from Libya to the Philippines. They were freed from Sirte when local forces drove IS group from the city last year.

IS group took full control of Sirte in early 2015, turning it into their North African stronghold and holding dozens of foreign captives. The Philippine nationals are medical staff who were among foreign workers already in the city when it came under the ultra-hardline group's rule.

"When they found out we were Muslims they released us but under a strict condition that we will have to work as nurses in their hospital and we had to train IS (Islamic State) on emergency care and nursing course," the nurse told reporters in the Libyan capital, Tripoli.

"It was a horrible time. Each day we lived in fear. We didn't know what was going to happen next. And they threatened to kill us if we left Sirte."

The Philippine staff worked at Sirte's main hospital, which IS group used to treat their wounded militants  until they were pushed out of central Sirte in August.

Militants then retreated towards their final strongholds near Sirte's seafront, taking medical equipment and foreign captives with them.

IS group was defeated in Sirte in early December, after nearly seven months of fighting. The Philippine medical staff and many of the other foreign captives were freed in the final stages of the battle.

Since then they have been held in Misrata, the city that led the military campaign in Sirte. Also held there are dozens of women from sub-Saharan Africa who were captured while crossing Libya as migrants and used as sex slaves in Sirte.

Earlier this month an Indian doctor who had also been trapped in Sirte, Ramamurthy Kosanam, was flown out of Libya.

He said on Sunday that he had worked in field hospitals run by IS group for about two-and-a-half months, and was shot in the hand and both legs during battles before being rescued by local Libyan fighters.